Middle Palaeogene dinoflagellate cysts from Tierra del Fuego, Argentina: biostratigraphy and palaeoenvironments

Guerstein, G. Raquel; Guler, M. Verónica; Williams, Graham L.; Fensome, Robert A.; Heider, Guillermo

doi:10.1144/jm.27.1.75

Cited by 34 publications

(43 citation statements)

References 37 publications

(54 reference statements)

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“…This is likely because the surface waters were influenced by the low-latitude eastward flowing proto-Leeuwin current along the northern margin of the AAG (Figure 9), much like the Modern. Trans-Antarctic endemic dinocyst taxa are dominant at ODP Site 1172, ODP Site 696, and at DSDP Site 511, in-line with reports of similar endemic trans-Antarctic assemblages in middle-late Eocene strata from adjacent regions (e.g., Guerstein et al, 2008;Mohr, 1990;Wrenn & Hart, 1988). It implies that the East Tasman Plateau, the Weddell Sea, and the southwest Atlantic were influenced by Antarctic-derived surface waters (Figure 9a).…”

Section: Late Eocene Surface Oceanographic Changesupporting

confidence: 85%

Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full‐Scale Glaciation

Houben

Bijl

Sluijs

et al. 2019

Geochem Geophys Geosyst

210

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During the Eocene‐Oligocene Transition (EOT; 34–33.5 Ma), Antarctic ice sheets relatively rapidly expanded, leading to the first continent‐scale glaciation of the Cenozoic. Declining atmospheric CO2 concentrations and associated feedbacks have been invoked as underlying mechanisms, but the role of the quasi‐coeval opening of Southern Ocean gateways (Tasman Gateway and Drake Passage) and resulting changes in ocean circulation is as yet poorly understood. Definitive field evidence from EOT sedimentary successions from the Antarctic margin and the Southern Ocean is lacking, also because the few available sequences are often incomplete and poorly dated, hampering detailed paleoceanographic and paleoclimatic analysis. Here we use organic dinoflagellate cysts (dinocysts) to date and correlate critical Southern Ocean EOT successions. We demonstrate that widespread winnowed glauconite‐rich lithological units were deposited ubiquitously and simultaneously in relatively shallow‐marine environments at various Southern Ocean localities, starting in the late Eocene (~35.7 Ma). Based on organic biomarker paleothermometry and quantitative dinocyst distribution patterns, we analyze Southern Ocean paleoceanographic change across the EOT. We obtain strong indications for invigorated surface and bottom water circulation at sites affected by polar westward‐flowing wind‐driven currents, including a westward‐flowing Antarctic Countercurrent, starting at about 35.7 Ma. The mechanism for this oceanographic invigoration remains poorly understood. The circum‐Antarctic expression of the phenomenon suggests that, rather than triggered by tectonic deepening of the Tasman Gateway, progressive pre‐EOT atmospheric cooling played an important role. At localities affected by the Antarctic Countercurrent, sea surface productivity increased and simultaneously circum‐Antarctic surface waters cooled. We surmise that combined, these processes contributed to preconditioning the Antarctic continent for glaciation.

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Section: Late Eocene Surface Oceanographic Changesupporting

confidence: 85%

Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full‐Scale Glaciation

Houben

Bijl

Sluijs

et al. 2019

Geochem Geophys Geosyst

210

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“…From the middle Eocene onward, endemic dinoflagellates consistently and strongly dominate the assemblages along the western boundaries of the Drake Passage and the Tasman Gateway as well as at Prydz Bay (Figures 2d, 2e, and 2f, 47 Ma to 39 Ma), at least until the mid to late Eocene (Figure 2g, 38–36 Ma). Many undoubtedly Oligocene and younger records in the southwest Pacific (not presented here; e.g., ODP Leg 28 [ Kemp , 1975]) and Atlantic [ Guerstein et al , 2008] yield some endemic dinocysts. These are most likely reworked from Eocene sediments as a result of Oligocene glacial activity.…”

Section: Resultsmentioning

confidence: 95%

Environmental forcings of Paleogene Southern Ocean dinoflagellate biogeography

et al. 2011

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[1] Despite warm polar climates and low meridional temperature gradients, a number of different high-latitude plankton assemblages were, to varying extents, dominated by endemic species during most of the Paleogene. To better understand the evolution of Paleogene plankton endemism in the high southern latitudes, we investigate the spatiotemporal distribution of the fossil remains of dinoflagellates, i.e., organic-walled cysts (dinocysts), and their response to changes in regional sea surface temperature (SST). We show that Paleocene and early Eocene (∼65-50 Ma) Southern Ocean dinocyst assemblages were largely cosmopolitan in nature but that a distinct switch from cosmopolitan-dominated to endemic-dominated assemblages (the so-called "transantarctic flora") occurred around the early-middle Eocene boundary (∼50 Ma). The spatial distribution and relative abundance patterns of this transantarctic flora correspond well with surface water circulation patterns as reconstructed through general circulation model experiments throughout the Eocene. We quantitatively compare dinocyst assemblages with previously published TEX 86 -based SST reconstructions through the early and middle Eocene from a key locality in the southwest Pacific Ocean, ODP Leg 189 Site 1172 on the East Tasman Plateau. We conclude that the middle Eocene onset of the proliferation of the transantarctic flora is not linearly correlated with regional SST records and that only after the transantarctic flora became fully established later in the middle Eocene, possibly triggered by large-scale changes in surface-ocean nutrient availability, were abundances of endemic dinocysts modulated by regional SST variations.

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“…El potencial de los quistes de dinoflagelados como indicadores bioestratigráficos en el Paleógeno del Hemisferio Sur se ha visto notoriamente incrementado en los últimos años a través de los estudios realizados sobre testigos de ODP e IODP en el Pacífico Sur (Bijl et al, 2013b y trabajos allí citados). Asimismo, trabajos recientes sobre secciones aflorantes en el sudoeste de la Cuenca Austral (González Estebenet et al, 2014bGuerstein et al, 2008bGuerstein et al, , 2014 constituyen una importante fuente de información que puede ser considerada para analizar los resultados obtenidos en las cuencas de latitudes medias. En este caso, utilizamos los eventos de quistes de dinoflagelados de las especies diagnósticas basadas en la bioestratigrafía de alta resolución propuesta por Bijl et al (2013b) para el Paleógeno del Pacífico Sur (South Pacific Dinocyst Zones, SPDZ) y las asociaciones de quistes de dinoflagelados para la transición Eoceno-Oligoceno de Sluijs et al (2003).…”

Section: Edad De Las Secciones Estudiadasunclassified

“…Durante el Eoceno tardío los componentes endémicos en los distintos sitios de la Plataforma del Océano Atlántico Sudoccidental fueron reemplazados por asociaciones más diversas con indicadores de aguas frías y especies típicamente oceánicas, con un incremento de quistes de dinoflagelados heterotróficos modernos de la familia Protoperidiniaceae (Guerstein et al, 2008b;González Estebenet et al, 2015). La apertura y profundización del Conducto de Tasmania y el Pasaje de Drake y el subsecuente desarrollo de una incipiente Corriente Circumpolar Antártica durante el Oligoceno produjo la disrupción de los giros subpolares y la extinción de las especies endémicas-antárticas Houben et al, 2013).…”

Section: Consideraciones Finalesunclassified

“…Estudios posteriores reconocieron a las especies pertenecientes a esta comunidad antártica en numerosas localidades del Océano Austral (Wrenn & Hart, 1988;Cocozza & Clarke, 1992;Mao & Mohr, 1995;Truswell, 1997;Levy & Hardwood, 2000;Brinkhuis et al, 2003a,b;MacPhail & Truswell, 2004;Guerstein et al, 2008b;Sluijs et al, 2009;Bijl et al, 2011Bijl et al, , 2013aGuerstein et al, 2014;González Estebenet et al, 2014a,b). La asociación endémica-antártica proliferó hasta el final del Eoceno, cuando se modificaron los patrones de circulación oceánica como consecuencia de la profundización del Pasaje de Drake y el Conducto de Tasmania Stickley et al, 2004a;Guerstein et al, 2008b;Houben et al, 2011Houben et al, , 2013. Dichos cambios provocaron la consecuente extinción de las especies endémicas, que fueron reemplazadas por taxa cosmopolitas (Stickley et al, 2004b;Bijl et al, 2011;Houben et al, 2013;González Estebenet et al, 2015).…”

Section: Introductionunclassified

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Dinoflagelados del Eoceno medio a superior de las cuencas Punta Del Este y Colorado, latitudes medias del Atlántico sudoccidental

Daners¹,

Guerstein²,

Amenábar³

et al. 2016

Rev. bras. paleontol.

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-MIDDLE TO UPPER EOCENE DINOFLAGELLATE CYSTS FROM PUNTA DEL ESTE AND COLORADO BASINS, MID LATITUDE SOUTHWEST ATLANTIC OCEAN. The analysis of middle Eocene dinoflagellate cystassemblages from sites at Punta del Este (~36°S, Uruguay) and Colorado (~38°S, Argentina) basins allows to interpret ocean circulation patterns on the South American Shelf prior to the opening of the Drake Passage. The assemblages contain endemic-Antarctic taxa such as Enneadocysta, Deflandrea, Vozzhennikovia and Spinidinium, which are also dominant in several circum-Antarctic sites, located southern 45°S. Enneadocysta dictyostila is the most abundant species recorded from the studied sites and the unique member of the endemic assemblage apparently tolerant to warm surface waters. The presence of endemic taxa at mid latitudes has been related to a strong clockwise subpolar gyre favoured by the partial continental blockage of the Tasmanian Gateways and the Drake Passage. The distribution of the dinoflagellate cyst assemblages along the South Atlantic Ocean Shelf can be explained by a similar dynamical mechanism induced by a cyclonic subpolar gyre on the South Atlantic Ocean. The western boundary current of this gyre, starting on the west Antarctic continental slope, would follow a similar path to the present Malvinas Current on the Patagonian slope, which introduce cold oceanic waters to the shelf and intensifies the northward shelf transport. In the same way, during the middle Eocene the western boundary current of a proto-Weddell Gyre transported the circum-Antarctic waters and the endemic taxa northward along the Southwestern Atlantic Shelf. The opening and deepening of the Tasmanian Gateway and Drake Passage and the development of an incipient Antarctic Circumpolar Current during the latest Eocene-Oligocene disrupted the subpolar gyres and promoted the extinction of the endemic species.Key words: dinoflagellate cysts, Eocene, Punta del Este Basin, Colorado Basin, biostratigraphy, paleoceanography. RESUMO -O estudo de associações de cistos de dinoflagelados do Eoceno médio nas bacias de Punta del Este (~36°S,Uruguai) e do Colorado (~38°S, Argentina) permite interpretar os padrões de circulação oceânica na plataforma sul-americana antes da abertura da Passagem de Drake. As associações são caracterizadas pela presença de táxons antárticos endémicos, como Enneadocysta, Deflandrea, Vozzhennikovia e Spinidinium, dominantes em vários locais da região Circumpolar Antárctica localizados ao sul do 45°S. A espécie mais abundante registrada nos locais estudados é Enneadocysta dictyostila, que é o único membro da associação endêmica aparentemente resistente às águas aquecidas na superfície. Pesquisas anteriores já haviam mencionado a presença de táxons endêmicos em latitudes médias a um forte giro subpolar no sentido horário favorecido pelo bloqueio parcial das passagens da Tasmânia e de Drake. Propõe-se aqui, que a distribuição das associações de cistos de dinoflagelados, ao longo das bacias da margem continental do Atlântico Sul, pode ser e...

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Middle Palaeogene dinoflagellate cysts from Tierra del Fuego, Argentina: biostratigraphy and palaeoenvironments

Cited by 34 publications

References 37 publications

Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full‐Scale Glaciation

Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full‐Scale Glaciation

Environmental forcings of Paleogene Southern Ocean dinoflagellate biogeography

Dinoflagelados del Eoceno medio a superior de las cuencas Punta Del Este y Colorado, latitudes medias del Atlántico sudoccidental

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